Wide-band wavemeter



H. F. MATARE WIDE: BAND WAVEMETER May 19, 1953 Filed NOV. 25, 1949 Patented May 19, 1953 lambert .liranecis .Matera Vaueressoia France.

assigner tc Setietef Anonyme dite.: Qnmrasnie des Freins .France &. ignaux Westinghouse, Paris Application November 23, 1949, lSerial No. 129,025"

En France' December 4;, 19.48

` 4 Qlaims.. (Cl. 250g-153,9)

. Wavemetersai the remnant cavity type and I it,

Casaetv @lees riot ex-.eed a value in the order of a iewmicrefarads in the range of ultra-high frequencies. mother words, the amplitude of ,capacity adjustment in such wavemeters is restricted by mechanical limitations.

This invention has for its object to provide a wavsmetelf' which is free of this drawback.. and' in which the variable capacity may be adjusted ever avide .range ,so that they meter is. a ed, i;or. usey over a comparatively Wide fgregu vey ttige.

y The Wavemeter 0f the inventan is characterized by the following ieatures considered singly or in combination:

(l).l @The variable capacity' is formed by a iixed and. a rctatable electrcde.. Beth electrodes are formed with offsets, steps or shoulders in an axial direction and oppositely related each other, and the rotary electrode is arranged at the end of a control spindle provided with a control knob at its other end;

(2) On the rod of the rotary electrode a sleeve is mounted with a soft sliding t, adapted to loel moved withinv a resonant cavity axially thereof, said sleeve being in movable threaded engagement with a tapped hole formed in the frame of the apparatus and being rigid With an actuating bush;

3) The Xed electrode of the capacity is connected with a plug socket for connection with the output of the apparatus supplying the frequency to be measured, while a. detector located within the resonant cavity is magnetically coupled with the internal eld, said detector having its output connected with one, interchangeable electrode of a capacitor the other lelectrode of which is earthed.

Further characteristic features and advantages of the invention Will appear from the ensuing description and the accompanying diagrammatic drawings which illustrate by way of example only, one form of embodiment of the invention, and in which:

Fig. 1 is a sectional View of a waverneter according to the invention, and

Fig. 2 is an overhead plan view thereof.

As shown in the drawings, the wavemeter comprises a resonant cavity I having a bottom plate 2 ca which-is. secured through. the interposalpf au insulatiug: washer 3 (made: of trolitul or eeuws alent composition) and electrode 4 cooperating' with. .further and. movable electrode 5 disposed at the Grid ef; a,V rotary control shaft or spindlev a to form a capacity. The control spindle 6, is. provided at its tcp end'with an actuating button or knob 'i carrying a pointer.' 8 movablein front of a circular calibrated scale 9. The topv of the spindle- 6 is mountedin tubular part It rigid with a volse member I I to which the Scalea is secured.

and which. itself is. secured to the top plate t2 of.-A the reasonarit cavity.

Each 0f. the electrodes 4 and 5. is formed asr shown in 1v1-ith complementary space itely` fermedaxial oiisets, steps or shoulders I3 and I5, respect' ely, whereby thetapacty may be varied Wit, predetermined range by Circular movement. y i. g

The fixed electrode 4 is connected with-a plug toelaat.l I5.4 ier ,connection with the output of an apnaratus the output frequency of which is to.

be measured.

Within the resonant cavity I is arranged a deto earth through a part 22 threaded over thev bushing 2| and forming part of a connecting socket the other part of which is shown at 23. The socket 22-23 enables the wavemeter to be wired into a suitable circuit.

The electrode I8 is removable to allow replacement by another electrode of different diameter in order to alter its capacity.

Over the spindle 6 of the rotary armature 5 an externally threaded sleeve 24 is mounted a soft sliding t, and the sleeve 24 is screwed into a com. plementarily tapped bushing 25 rigid with the top plate I2 of the resonant cavity I. The sleeve 24 is rigid with an actuating bushing 26 having a bevelled lower edge which may carry an index marker movable in front' of a calibration carried by the bushing 25. a

To modify the initial capacity, the button 1 is rotated thereby rotating the spindle 6 and the movable electrode 5, as a result of which the capacity is varied from a minimum value (corresponding with the position shown in Fig. l)

to a maximum value corresponding with a 180 rotation of, the movable electrode 5. The wide range of possible adjustment of the wavemeter of the invention is secured by actuation of the bushing 2,6 which moves the sleeve 24 up and down, thereby adapting the effective volume of the resonant cavity to the limiting conditions of the operating range of the apparatus.

The scale 9 may be graduated, after having been suitably calibrated, either in wavelengths for a given detector, or in angular graduations.

In the latter case reference tables may be usedv to ascertain the wavelength for each one of the various types of detectors used.

It will bei, seen as a result of the foregoing that the wavemeter herein described provides a measuring instrument of high accuracy usable over a wide frequency range.

Besides, the same apparatus could be used for reception of high frequency input signals by means of the plug socket l5, the low frequency output being collected through the plug socket 22-23. It will be understood that many alterations may be made in the structural details of the wavemeter described and illustrated for purposes of indication land not of limitation, without exceeding the scope of the invention.

I claim:

y l. A cavity resonator comprising a resonant cavity, a variable capacity in said cavity including a fixed-and a rotatable electrode, offset means at the adjacent ends of said electrodes to vary the capacitance'therebetween on rotation of the rotatable electrode, a sleeve surroundingl and freely slidable on lsaid rotatable electrode and projecting into said cavity and means for moving said sleeve axially to vary the extent of said sleeve projects into the cavity to adjust the effective resonant volume of said cavity and a detector projecting into said cavity through a side thereof and coupled with the field set up by the electrodes in said cavity.

2. A resonator according to claim 1, in which the detector comprises two elements electrically insulated from one another to form a capacity and a probe electrode projecting inwardly from one of said elements toward the aforementioned movable electrode.

3. A resonator according to claim 2, in which the probe electrode is removably secured to the element from which it projects and is one of a series of interchangeable electrodes.

4. A cavity resonator comprising a resonant cavity, a variable capacity in said cavity including axially aligned electrodes placed with adjacent ends close to one another, one of said electrodes being stationary relative to the cavity and the other being rotatable about its longitudinal axis, the adjacent ends of said electrodes being formed with eccentric portions to vary the capacitance therebetween on rotation of the rotatable electrode, a sleeve surrounding and freely slidable on one of said electrodes, means for adjustably moving said sleeve axially toward and away from the other of said electrodes, the rotary movement of said rotatable electrode and the axial movement of said sleeve being independent of one another and a probe projecting into the cavity and coupled with the iield therein.

HERBERT FRANors MATAR.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date Re. 22,894 Lavoie July 1, 1947 1,620,020 Hardy Mar. 8, 1927 Y2,444,041 Harrison June 29, 1948 2,488,545 Lader Nov. 22, 1949 2,503,256 Ginzton et a1 Apr. 11, 1950 2,556,607 Wheeler June 12, 1951 FOREIGN PATENTS Number Country Date 430,645 Great Britain June 21 1935 

